Apparatus for developing underwater reservoirs



May 29, 1956 T. MILES 2,747,840

APPARATUS FOR DEVELOPING UNDERWATER RESERVOIRS Filed June 12, 195: a Sheets-Sheet 1 WATER LEVEL INVENTOR. T. MILE 5 BY M Y ATTORNEYS May 29, 1956 T. MILES 2,747,840

APPARATUS FOR DEVELOPING UNDERWATER RESERVOIRS Filed June 12. 1953 3 Sheets-Sheet 2 FIG. 9.

37 I I39 I I3! I 35 I37 i UH y ,0, 0- 5| 87 o 93 INVENTOR. 9P4 45 v T.M|LE5 ATTORNEYS May 29, 1956 T. MILES 2,747,340

APPARATUS FOR DEVELOPING UNDERWATER RESERVOIRS I Filed June 12, 1955 3 Sheets-Sheet 3 INVENTOR. T. MILES ATTORNEYS United States Patent APPARATUS FOR DEVELOPING UNDERWATER RESERVOIRS Theodore Miles, Long Beach, Calif., assignor to Phillips Petroleum Company, a corporation of Delaware Application June 12, 1953, Serial No. 361,188

7 Claims. (Cl. 255--2.5)

This invention relates to apparatus for developing underwater reservoirs. In one aspect it relates to apparatus for developing and producing reservoirs off-shore without obstructing navigation. In another aspect it re lates to apparatus for developing reservoirs lying beneath water and oif-shore, such as under bays and inlets without obstructing normal navigation by construction of islands or the like.

Oil is found under bodies of water, such as bays, lakes, rivers, seas and oceans. It is old to exploit such fields by drilling wells from barges upon which are mounted the usual drilling equipment such as drawworks, derricks, pumps, etc. The usual procedure is to float the drilling barge to the location and then open the sea valves to the ballast tanks and sink the barge hull to the bottom when water is sufficiently shallow. In deeper water one or more barges are sunk and the drilling barge sunk to rest upon the other barges as a base. These barges are ordinarily formed with open slots-so that upon completion of the well the barge may be refioated and moved to another location without interfering with well casing or other piping. If piling has been driven for support of drilling equipment a platform may be mounted on this piling to provide Working space. A small platform may be allowed to remain on at least some of the piling for use during production operations. If piling had not been used during drilling operations piling may be driven into the ground for use as a support for a production platform after removal of the drilling equipment. Such a production platform then becomes permanent equipment as long as the well is being produced and such permanent-equipment obviously interferes with navigation in case the well has been drilled in navigable waters.

Other methods for drilling wells in bodies of water involve construction of islands where the drilling equipment may be set. Such islands are a menace to and interfere with navigation. Frequently such permanent construction may be used in the open sea without objection. When it is desired to drill wells, for example, within a harbor area obviously construction of permanent islands or platforms within the harbor is highly objectionable. Drilling of wells in such locations ordinarily requires government approval. It is obvious that such approval would not be forthcoming if obstruction to navigation were permanent.

One method for developing underwater reservoirs provides for directional drilling from on-shore locations. It is obvious that this method is limited and is not easily adaptable for the development of reservoirs appreciable distances off-shore. One suggested method is to sink a shaft to such a depth in the ground that horizontal tunnels therefrom extending under the water will be a safe working distance below water. Tunnels may be run any distance desired under the water and at any desired location. Caverns may be excavated for accommodation of well drilling equipment. It is obvious that such ice underground methods for developing underwater reservoirs would be extremely expensive.

I have devised an apparatus for use in developing underwater reservoirs which after drilling of a well and during its producing life would not interfere in any manner whatever with navigation. However, during the actual drilling operation navigation may be interfered with. My apparatus includes reinforced concrete cellar units, and a reinforced concrete tunnel or pipe alley for communication from the cellars to the shore. These cellars and pipe alleys are constructed on shore in sections. A ditch or channel is dredged from a position in the body of water to the shore line. Two or more cellar units may be assembled one to another on shore or on a barge, if desired, and the assembly floated to its point of use and lowered into the dredged channel or ditch, the channel or ditch, of course, being dredged sufficiently deep so that the top of the cellars will be at least flush with the normal bottom of the body of water. Additional cellar units may be added to those previously lowered for providing for drilling of a plurality of Wells. To the cellar assembly then will be added alley or tunnel units such as rectangular pre-cast units or circular concrete pipe units for providing a tunnel or passageway from the cellars to the shore. To drill a Well a drilling barge is floated to location and sunk to rest on one or more of the previously provided cellars or the barge may be supportedby props which in turn are supported by the cellar units and a large diameter pipe or tube lowered through an opening in the barge to the top of the cellar. This large diameter pipe is bolted water tight to the top of the cellar and then the water within the cellar units, tunnel and tubing is pumped out. The plate covering the opening in the top of the cellar unit is of course removed and access is therefore provided from the drilling barge to the space within the cellar. When a well is completed this plate is bolted to its original position on the top of the cellar and the large diameter pipe removed and the barge can then be refloated and moved to another location for drilling another well. Since the top of the cellar units and access tunnel unit are about flush with the bottom of the body of water after removal of the drilling equipment the body of water is then suitable for navigation.

In the drawing:

Figure 1 is an elevational view, partly in section, of an assembly of apparatus parts for developing a reservoir according to my invention.

Figure 2 is a plan View of an assembly of apparatus for developing underground reservoirs according to my invention.

Figure 3 is a cross-sectional view taken on the line 3-3 of Figure 2.

Figure 4 is a plan view, partly in section, of a portion of the apparatus parts of my invention.

Figure 5 is a cross-sectional view taken on the line 5-5 of Figure 4. 1

Figure 6 is an end view of the apparatus of Figure 7 taken from the line 6--6.

Figure 7 is a side elevation, partly in section, of the apparatus of Figure 6.

Figure 8 is an end view of the apparatus of Figure 7 taken from the line 8-8.

Figure 9 is the plan view of another embodiment of drilling barge suitable for use with the apparatus of my invention.

Figure 10 is a plan view of still another embodiment of drilling barge suitable for use with the apparatus of my invention.

Figure 11 is a plan view of another embodiment of the apparatus parts of my invention.

Figure 12 is a side elevational of another arrangement of apparatus parts of my invention.

Referring now to the drawing and specifically to Figure 1 reference numeral 11 identifies a fioatable drilling barge in operative position on top of an assembly of cellar units 73 of my invention for drilling a well. A cellar unit is illustrated on an enlarged scale in Figures 4 and 5. On reference to Figure 4 a cellar unit 73 of this embodiment comprises two sections, a pipe alley section 93 and a cellar section 91. This entire unit as illustrated in Figure 4 is of p're-cast reinforced concrete. Unitsof this nature can be cast at more or less permanent shore installations and carried on a barge to their point of use in the body of water, and then lowered into a properly excavated channel. This cellar unit 73 as mentioned above is composed of two separate sections, these sections being separated by a partition 72. This partition is of course ca'st integrally with the unit. An opening 74 is provided in either end of the alley section 93 for access to adjoining sections. If desired, an opening 80 (Fig. 5) may be provided in the top "or roof of this alley section and covered with a cover plate 23. The cellar section of this assembly is provided with one or two openings 76, one of which may be seen in Figure 5. Immediately below this opening'is another opening 79 in the bottom or floor of this cellar section 91. The ends of the alley sections are provided with metal frame connectors 75 for attachment to adjoining alley sections. If desired these connectors 75 are so constructed with frames on the interior of the alley sections that these sections may be attached to one another by bolts 77 or other means from within. When opening 76 in the top of the cellar section 91 is not in actual use it is covered with a cover plate member 23 so as to exclude water. A similar cover .plate 23 'is shown as covering opening 80 in the top of the alley section of this cellar unit. The partition 72 separating the alley section from the cellar section is also provided with an opening 87 for passage of men and materials during drilling or producing operations. If desired this opening may be closed by a cover plate 89. Other openings 107 are also provided in partition 72 for accommodation of an oil production pipe from the well head to the alley, and other oil, gas and water pipes.

When each cellar'section 91 is provided with two openings 76 and two openings 79, two wells may then be drilled through each cellar section. 'Under some conditions it may be desired to provide each cellar section 91 with only one opening 76 and one corresponding opening 79 for use in drilling only one "well from each cellar section. As many cellar'units as desired may be installed adjacent one another or at spaced intervals along the alley 71 for the drilling of any desired "number of wells.

Wells may be drilled from very -close surface spacing on a directional basis to different horizons, for example, as many as or 12 wells may be drilled from a general location with for example, one wellbein'g drilled in each of four directions to one oil containing formation and another set of four wells, for example, can be drilled directionally to another and deeper oil containing formation, while still other wells may be drilled straight downward or directionally to still other'form'ations. In this manner all of these wells may be drilled from one drilling barge with the use of one assembly of cellars and alley. The produced oil from the well heads maybe manifolded into one production line extending through the alley to separator tanks or one flow line may be provided for each well and run into individual separator tanks as desired.

In Figure 5 reference numeral 69 identifies reinforcing rods used in the construction of this cellar unit. Reinforcing rods identified by reference numeral 69 are also illustrated in the alley section 71.

As stated above, the alley sections 71 of Figure. 4 are shown as being fastened together by metal frame connectors 75 with bolts 77 from within the alley, however, it is not necessary that these sections be bolted together from within the alley. In this latter case flanges, not shown, may be provided for metal frame connectors similar to connectors 75 for outside flanges. However, inside flanging is preferable since in many cases work on the alley may be carried out from within the water-free alley. in Figure 4 is illustrated a tunnel or alley section attached to one end of the alley section '93 for leading to, for example, a cellar unit similar to cellar unit 73 at some remote point at which it is desired to drill one or more wells.

The alley sections 71 and 85 may, if desired, be of square or rectangular crosssection or if desired may be of circular cross-section. The circular type is preferable because of simplicity of construction. When circular alley sections are used a coupling section will need to be provided for changing from the rectangular crosssection of alley section 93. Such a coupling member is illustrated in Figure 7 and identified therein by reference numeral 97. In this figure it is intended for the right hand end to be square in cross-section and the left hand end to be of circular crosssection. Reference numeral 101 identifies the square end of coupling 97 while reference numeral 99 identifies the circular end. Figure Sis an end view of this coupling element looking into the square end, while Figure 6 is an end view looking into the circular end. Connecting element 193 is for attachment of circular sections leaving a round opening 104 therebetween and reference numeral 74 identifies square openings.

When a sufiicient number of cellar units have been installed and fastened together water tight and the access tunnel or alley run from the cellars to the shore this apparatus is then ready for beginning of well drilling operations.

When the cellar and tunnel apparatus is made and installed as above described, a suitable drilling barge equipped with well drilling apparatus is then floated to location. The bottom side of the barge 11 is provided with props or supports 13 which are intended to extend from the undersurface of the barge to a level slightly above the top of the assembly of cellars. When the barge is in proper location, that is, when a drilling slot or other opening is immediately over an opening 76 (Figure 5) water is pumped into ballast tanks to lower the barge until the props 13 contact the top of the eel lars and the barge 11 is held rigidly in position. in Figure l ballast tanks are illustrated adjacent either end of the barge filled to levels 67 with water. When the barge is so positioned a large diameter pipe 21 is low e'red through the b'arges drilling slot in such a manner that a flange on the bottom of the pipe is properly position'e'd with respect to bolts 73 for holding this tube rigidly in position and water tight with respect to the cellar. This tube 21 is of such length that it extends to a distance above water level such that water will not enter the tube even during high tide periods. ln this installation so far the alley sections, the cellar sections and pipe 21 are full of water. The next operations are for the purpose of sealing out water which might enter the cellars through opening 79. A conventional conductor pipe 25 is lowered through the large diameter tube 21 and through the opening 79 in the bottom of the cellar unit 91. This conductor pipe is forced into the ground to such a depth as to make certain that water cannot leak into it from the bottom. After cementing or otherwise sealing the space between this pipe and opening 79, the water in the cellar is pumped out and the conductor pipe is cut off at about the level of the floor 17 of the cellar section 91. The earthy material within this conductorpipe 25 is then drilled out and the drilling is continued to a depth some little distance below the lower end of the pipe. A section of surface pipe 27 is then lowered through the conductor pipe and nearly to the bottom of the drilled out section below the end of the conductor pipe. The outside diameter of the surface pipe 27 is somewhat smaller than the inner di ameter of the conductor pipe to provide an annulus between these pipes. The surface pipe is then filled with a cement slurry which is forced into this pipe and out its bottom and up the annulus between this pipe and the earth below the conductor pipe and through the annulus between the two pipes until the annulus is at least completely filled. It is preferable to use a sutficiently large amount of cement that at least some of the cement which rises through the annulus will overflow from the top of the conductor pipe. At this stage sufficient time is permitted to elapse for this cement to set and become somewhat hardened. When the cement has become sufficiently hard a hole is drilled down through the cement inside the surface pipe sufliciently large to accommodate the largest diameter casing intended to be used in the well. After drilling through this cement the well is then drilled in a normal manner and to such a depth as desired. One or more tanks 55 are provided on the barge for accommodation of drilling mud. This drilling barge isprovided with more or less conventional well drilling apparatus such as a derrick 37, a hoist or draw works and other necessary equipment.

Just prior to the beginning of actual drilling operations such equipment as a blow-out preventer 39 is installed on top of the surface pipe 27 and drilling is carried out through this piece of equipment.

When the well has been drilled to the desired depth, the drill tubing and bit are removed from the well and the christmas tree assembly is installed. Finally, the drilling mud is pumped out. To one outlet of this christmas tree is then installed a flow pipe for carrying the oil and/or gas from the well to some separator tanks,

not shown in Figure 1. In case the well has to be pumped, a fluid powered pump, such as one utilizing crude oil as the power liquid or a gas-lift pump can be used. Such pumps are preferable for use in conjunction with the cellar units of my invention because little head room is required for such a well or casing head 51, Figure 1. Another completed well of this assembly includes corresponding parts, as a conductor pipe 25', surface pipe 27, cement 29', and well casing 49.

When one well of such a plurality of wells has been completed, water may be pumped from the ballast tanks and the barge floated a suflicient distance on top of the cellars for positioning for drilling another well. 7

If however, a drilling barge such as that illustrated in Figure 9 is used the barge need not be floated from one position to another for drilling several wells. This type of barge in place of being provided with a small opening for passage of the various pipes or tubes and drilling equipment is provided with an elongated slot 125. On either side of this slot 125 is provided rails or tracks 123. In this case the derrick is mounted on rollers and the derrick is merely rolled from one position to another. This type of operation can be continued until the end of the slot 125 has been reached when the barge must be floated to a new position for drilling additional wells. In further reference to Figure 9, the drilling barge is identified by reference numeral 121, the open slot by numeral 125 and tracks or rails by 123 as mentioned above. Reference numeral 127 identifies the movable derrick. Another embodiment suitable for carrying out this latter general type of operation is illustrated by the barge of Figure 10. In this embodiment in place of having an elongated slot there are provided a plurality of slots 137 which may either be square or circular in section and more or less similar to the slot described in conjunction with the barge 11 of Figure 1. Thus with the use of the barge of Figure 10 the barge need not be moved for the drilling of several wells but merely the derrick 139 is moved along its track 133 on barge 131.

On reference to the plan view of Figure 2, reference numeral 57 is intended to represent a directionally drilled well. Reference numeral 59 is intended to be another well drilled in a direction as illustrated. Still another well 63 is drilled in a direction opposite to that of well 59. A well 65 is drilled in the same general direction from the barge as is well 63. Wells 63 and 65 are shown intentionally as being drilled in the same general direction but it is intended that, for example, well 65 be drilled to a deeper formation than well 63 for the express purpose of producing oil from more than one horizon. Still another well 61 is illustrated as having been drilled directly downward. from its starting position under the barge and such a well may tap any one of a plurality of oil containing formations.

On reference to Figure 1 of the drawing reference numeral 33 is intended to identify connecting means for connecting alley units to one another in a manner for excluding all water. Reference numeral 31 is intended to be drill pipe. Reference numeral 29 is intended to be the cement which has been forced from the bottom of the surface pipe into the annulus between the surface pipe and the earth. Reference numeral 19 is the opening in the top of the cellar section 91 through which all working in the drilling operation is carried out. Reference numeral 41 identifies the cement which has overflown the top of the conductor pipe for sealing off the space between the conductor pipe and the walls of the opening 79 in the bottom of the cellar 91. Reference numeral 45 is an oil flow pipe leading from a producing well head 51 to receiving tanks, not shown.

When a well has been drilled and the christmas tree and other producing apparatus installed the cover plate 23 which was previously removed from the top of the cellar section is rebolted into the position from within the tubing 21 in such a manner as to exclude water from the cellar when tubing 21 has been removed. When this plate 23 has been reinstalled the tubing 21 is removed and water may then be pumped from the ballast tanks and the bargefloated to some other location.

If desired a pump may be installed within one or more of the cellar units for pumping out water in case water inadvertently leaks into the cellars.

In Figure 5, one or more openings 107 are provided in cellar wall 72 for accommodation of pipes carrying production fluid and power oil or gas. When these pipes are inserted through openings 107 the space around the pipes can be packed or sealed against leak-age of water if desired. Also if desired the pipe of the pumping assembly mentioned above for pumping out water which may inadvertently enter the cellars can be installed in an opening 107 along with the aforementioned pipes. In case water leaks appreciably into the cellars they may be pumped out prior to such time that an operator wishes to enter the cellar. Any opening or openings 107 not carrying a pipe can be plugged with a plug or other conventional type of closure means.

Details of construction of the reinforced concrete access tunnel sections and cellar sections are not specifically described since such construction is well known by those skilled in the art. All of these alley and cellar units, as mentioned above, are of pre-cast reinforced concrete construction and the connecting flanges, which are in place during the casting may be positioned at an angle so that the completed tunnel can follow any desired plan and at the same time, follow the general contour of the floor of the body of water. The connecting frame or flange elements should preferably be held rigidly in place by the reinforcing rods of the tunnel and cellar units.

Figures 11 and 12 illustrate one plan of development of reservoirs in which a plurality of wells is drilled at location 141 and one or more other wells are drilled at location 143. Wells at these two locations are connected to a single or a plurality of production lines 45 I for carryingproduction fluid to separator tanks-47. Alley units 71 connect the alley sections 73 of the cellar units. Alley section 151 is provided for extending the operations in case it is intended to carry development further from the shoreline.

The tunnel or alleyway of my invention may be used for many other purposes than for carrying oil producing pipes. Power oil or gas used for powering fluid operated pumps can be carried in pipes in the alley and can be manifolded to a plurality of pumps, or a separate pipe can be provided for each pumping well. A gas gathering pipeline system would be needed for collecting gas at the casing head of each pumping well. A water line in an alleyway might be the most convenient route for delivery of fresh water for drilling operations. A waste or cleanout line in the alley might be advantageous for transfer of mud and waste from the drilling barge to shore during drilling. An air line might be desirable for ventilation of the tunnel to remove combustible gases.

A conduit or conduits for electric power linesfor lighting,

from said cellar to the shore, said cellar and said alleyway being countersunk into the earth beneath a body of water to such an extent that the tops of said cellar and alleyway are about flush with the earth surface beneath said body of water, a barge support resting on said cellar, a floatable drilling barge at least partially submerged resting upon said barge support, a deep well drilling rig disposed on said barge, a first opening in the bottom of said cellar, said first opening being in water-tight contact with the earth, a second opening in the roof vof said cellar directly above said first opening, a tube attached water-tight to the cellar roof surrounding said second opening and extending to a level above the level of said body of water, the openings and said tube being adapted to accommodate casing and drilling equipment and said first opening being further adapted to accommodate production equipment.

2. An apparatus for off-shore drilling comprising, in combination, an underwater cellar disposed below the surface of the earth beneath a body of water to such an extent that the top of said cellar is about flush with the earth surface beneath said body of water, an access tunnel communicating with said cellar and extending to the shore, the shore end of said tunnel being above the high water level, a first preformed opening in the bottom of said cellar. said first opening being in water-tight contact with the earth, a second preformed opening in the roof of said cellar directly above said first opening, a tube attached water-tight to the cellar roof surrounding said second opening and extending to a level above the high water level of said body of water, a floatable drilling barge resting upon said cellar and access tunnel for drilling a Well through said openings and said tube.

3. An off-shore well drilling apparatus comprising, in combination, a cellar disposed below the surface of the earth beneath a body of water, the top of said cellar being disposed about flush with the earth surface, an access tunnel communicating with said cellar and the atmosphere on shore, a drilling barge disposed over said cellar, a watertight tube assembly extending from within the barge and above the waterline to said cellar, .said tube being attached water-tight to and communicable with said cellar and a well drilling assembly on said barge for drilling a well through'said tube and said cellar.

4. In the off-shore drilling apparatus of claim 3 wherein said-cellar comprises a cellar unit having a hollow working space therein, a first opening in the bottom of the cellar unit arranged watertight with respect to the ground below the body of Water, a second opening in one sidewall, the sidewall containing said second opening being operatively connected with said access tunnel in such a manner as to provide access from within said tunnel to the space within said cellar unit, a third opening in the top of said cellar unit in vertical alignment with said first opening and communicable with said water-tight tube assembly, to accommodate the drill of said well drilling assembly.

5. A deep well cellar assembly for providing manual and mechanical working space and for ingress and egress of operators to an off-shore well producing operation in a body of water comprising, in combination, a hollow cellar cell having a first opening in its bottom, a second opening in one side and a third opening in its top, means closing said third opening water-tight, the top of said cell being disposed at 'least'llush with the ground surface below said body of water so as to avoid interference with normal navigation, said first opening in the bottom of said cell being so disposed with respect to the ground and said body of water as to be substantially watertight, an access tunnel connected to the sidewall of said cellar cell containing said second opening in such a manner as to provide for passage of men and material, said access tunnel also communicating with the shore of said body of water in such a manner as to permit entrance and exit of men and material.

6. A deep off-shore well cellar assembly for producing fiuid from a well below a body of water and for providing manual and mechanical working space and for ingress and egress of working personnel and apparatus comprising, in combination, a hollow cellar cell having a first opening in its bottom, a second opening in one side wall and a third opening covered water-tight in its top wall, an access tunnel connected Watertight to said sidewall having said second opening in such a manner as to provide for communication between said tunnel and said cell, said tunnel also communicating with land on shore in such a manner as to provide for ingress and egress of men and material, said cellar cell and access tunnel being so countersunk into the ground below said body of water as to avoid interference with normal navigation in said body of water, a deep well producing apparatus extending through said first opening in the bottom of said cellar cell to a fluid containing formation, and a production pipe leading from the well head of said producing apparatus through said access tunnel to fluid storage on shore.

7. An off-shore deep well drilling and production assembly comprising a generally rectangular, hollow body member, a partition through said body member dividing same into two portions, one of said portions termed an access tunnel section and the other portion termed a working cellar, an opening in said partition providing access for men and material between said access tunnel section and said working cellar, a first opening in the bottom of said working cellar, a second opening being adapted to accommodate a cover plate in the top wall of said working cellar,

tunnel section and means for closing watertight the opening intheother'of said outside walls of said access tunnel.

References Cited in the file of this patent UNITED STATES PATENTS 1,050,271 vMcBean et al. Apr. 29, 19.13 1,647,448 Jones Nov. 1, 1927 2,331,072 Hansen et al. Oct. 5, 1943 

1. AN APPARATUS FOR OFF-SHORE DRILLING COMPRISING, IN COMBINATION, AN UNDERWATER CELLAR, AN ALLEYWAY LEADING FROM SAID CELLAR TO THE SHORE, SAID CELLAR AND SAID ALLEYWAY BEING COUNTERSUNK INTO THE EARTH BENEATH A BODY OF WATER TO SUCH AN EXTENT THAT THE TOPS OF SAID CELLAR AND ALLEYWAY ARE ABOUT FLUSH WITH THE EARTH SURFACE BENEATH SAID BODY OF WATER, A BARGE SUPPORT RESTING ON SAID CELLAR, A FLOATABLE DRILLING BARGE AT LEAST PARTIALLY SUBMERGED RESTING UPON SAID BARGE SUPPORT, A DEEP WELL DRILLING RIG DISPOSED ON SAID BARGE, A FIRST OPENING IN THE BOTTOM OF SAID CELLAR, SAID FIRST OPENING IN WATER-TIGHT CONTACT WITH THE EARTH, A SECOND OPENING IN THE ROOF OF SAID CELLAR DIRECTLY ABOVE SAID FIRST OPENING, A TUBE ATTACHED WATER-TIGHT TO THE CELLAR ROOF SURROUNDING SAID SECOND OPENING AND EXTENDING TO A LEVEL ABOVE THE LEVEL OF SAID BODY OF WATER, THE OEPNINGS AND SAID TUBE BEING ADAPTED TO ACCOMMODATE CASING AND DRILLING EQUIPMENT AND SAID FIRST OPENING BEING FURTHER ADAPTED TO ACCOMMODATE PRODUCTION EQUIPMENT. 